Possibly the Sanskrit word for China. There are two theories on where the Sanskrit word came from: One would be a pronounciation of 'Qin', ie the Qin dynasty, which was also used as the name of an western Chinese kingdom and, briefly, all China.

The other theory is that it is somehow related to 丝, the Chinese word for silk. This word may have also given rise to 'Seres' and 'Sino-' although it's all pure speculation.

Neither theory has any strict etymological proof (not helped by the fact that we only have a weak understanding of what ancient Chinese sounded like, and both theories have an eventual origin in Ancient Chinese), but that's the best anyone has been able to come up with.

Fun fact: "Han" can eventually be traced back to the name of a river in Sichuan (via a city named after said river, Liu Bang's headquarters for a time). Why the river was called that is unknown, and there were at least two other rivers with the same name.

China was famous for its porcelain, also called china. Foreigners called the country China because of that. At least, that's the only reason I've heard of.

http://www1.chinaculture.org/library/2008-02/11/content_22959.htm